DESCRIPTION: (Adapted from the application) This is a proposal to improve the utility of 2-D ultrasound imaging for use in clinical trials and cardiovascular epidemiology. The investigators will acquire B-mode images with commercially available ultrasound scanning equipment augmented with a spatial locator device. Computer software will be developed to combine multiple B-mode images into a three-dimensional ultrasound image of the deep wall of the vessel. The lumen and media/adventitia boundaries will be located in the composite image and a three dimensional map of wall thickness generated. From this map, areas of wall thickening will be localized and atherosclerosis measures such as size and distribution of discrete lesions and the extent of wall thickening above a specified threshold will be computed. Accuracy of lesion assessment will be estimated from phantom studies and overall precision of the method from repeat human scans. Twenty individuals participating in an on-going clinical atherosclerosis regression trial will receive ultrasound scans with a commercially available instrument at six month intervals for a period of 24 months and the computer method will be used to determine changes in wall thickness and lesion size.